The invention relates generally to the field of loudspeakers. In particular, the invention concerns improved loudspeakers, systems and components thereof.
A large percentage of loudspeakers used in audio systems are electrodynamic speakers. Such speakers employ a magnetic driver to produce movement of a diaphragm (typically cone or dome-shaped), which in turn causes sound.
A typical loudspeaker includes a frame upon which components are mounted. The frame provides a means for fastening the speaker to an enclosure or a receptacle. The frame, which is sometimes called the basket, has cut-outs in its side walls so air can freely circulate around a cone-shaped diaphragm. The loudspeaker driver includes a fixed magnet and voice coil. The magnet may be mounted to the rear of the frame behind the diaphragm. The voice coil is disposed adjacent the magnet and includes a bobbin. The bobbin is attached to the diaphragm.
In operation, electrical audio signals from an amplifier are applied to the voice coil producing a varying electromagnetic field around the coil. The electromagnetic field interacts with the magnetic field produced by the magnet. The magnet is securely fixed to the frame and the voice coil is movable, so the voice coil moves as the two fields interact. Because the voice coil is coupled to the diaphragm via the bobbin, its movement causes the diaphragm to vibrate. The vibration of the diaphragm causes air around the speaker to pressurize and depressurize, producing sound waves in the air.
Sound waves are emitted from both the front and rear of the speaker diaphragm. The waves emanating from the rear of an unmounted speaker can cause total or partial cancellation of the generated sound waves. To make speakers more efficient and improve sound quality, speakers are usually mounted within an enclosure.
A basic type of speaker enclosure is a sealed box structure. The structure is typically formed of wood or particle board and provides a sealed volume with air trapped inside. The speaker is positioned in an opening in the structure. The speaker frame has a flange with mounting holes formed therein. The speaker is positioned so that the flange is flush with one of the walls. Mounting screws can be inserted through the flange holes into the structure wall to secure the speaker within the sealed structure. The structure confines the rear pressure waves, thereby preventing interaction with the front waves resulting in better sound quality.
Speakers can be divided into three categories: woofer, midrange and tweeter. The woofer speaker reproduces low frequency (bass) sound ranging from about 20 to 3000 Hz. The midrange speaker reproduces a broad spectrum of sound, typically from about 1000 Hz to 10 kHz. The tweeter speaker reproduces high frequency (treble) sound ranging from about 4 to 20 kHz.